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LMX2820: register programming order for applying instacal data

mike leggett
Prodigy 80 points
Part Number: LMX2820

in changing the VCO frequency using the cal data I have collected, does it matter what order I set the registers?  I suspect that I would change the N divider first, then followed by the capctrl  and then the daciset.

In general the specifics of implementing integer frequency hoping using the instacal are vague.  Do you have a flow chart or other description I can code to?

thanks,

Mike

  • 0
    TI__Guru** 108410 points

    Hi Mike,

    If you use the instant calibration function of the LMX2820, you don't need to manually collect and apply the VCO parameters (capctrl, vco_sel, daciset), instant calibration will do it for you.

    Please follow the following procedure to run instant calibration.

    1. Open TICS Pro and select EVM default mode configuration
    2. In User Controls page, check all Double Buffer bits
    3. In PLL page, uncheck DBLR_CAL_EN in Instant calibration box
    4. Vcc power up the EVM
    5. Press Ctrl+L to program the EVM to lock to 6GHz
    6. Set INSTCAL_EN = 1 in Instant calibration box
    7. Type 5650 and then Enter in the VCO box (PLL_NUM, PLL_N and INSTCAL_PLL_NUM will be programmed automatically)
    8. Uncheck FCAL_EN in the VCO calibration box
    9. Check FCAL_EN
    10. Uncheck FCAL_EN and wait for a while (VCO will lock to 5650 MHz)
    11. Change VCO frequency, for example, type 5800 and then Enter in the VCO box (PLL_NUM, PLL_N and INSTCAL_PLL_NUM will be programmed automatically)
    12. Click Calibrate VCO button (this will write R0 once, VCO will lock to 5800 MHz)
    13. Change VCO frequency to 6200 MHz
    14. Click Calibrate VCO button (this will write R0 once, VCO will lock to 6200 MHz)